Paris green insecticide



Patented Dec. 3, 1929 Qumran STATES "PATENT OFFICE V nmwnrmr. WALLACE, or BROOKLYN, NEW YORK firms ennui: msnc'rrcmn Ho Drawing.

ll am aware that it has heretofore been pro- 1 used todistribute Paris green over the surjtace of stagnant water with a view to destroying the mosquito larvae when they rose to the surface to breathe, but owing to the specific density of such material, it was not w suficiently buoyant to remain onthe surface suficiently long and effective destruction of the mosquito larvae, due to the settling of the idly vued and the product is ready, when cooled, to

Paris green, could not be accomplished.

This was also true when certain inert filling materials were mixed with Paris green, as owing to the fact that such fillers ordiluents were of a greater density than water, they too, would settle out and the effectiveness of the rnixture'would be destroyed. W My investigations have led to the discove y that a highly efiective mosquito extermina r can he produced by the impregnation of the filler employed in the insecticide with relatively small quantities of a highly penetrative W and a relatively permanent waterproofing agent without deleteriously affecting the ineeeticidal properties of the insecticide prodnet, and that such product is peculiarly adapted for the destruction of mosquito larvae, hecause of the fact that a film of the same can he maintained for long periods of time on the surface of the water which forms the feeding placeof the mosquito larvae;

i; n carrying out my. invention, I preferably an proceed as follows 2- Li" ht, porous, flufly, calcium carbonate,

which carbonate compound is sufliciently light to float on water when water-proof in the manner hereinafter described, for exs ample: a calcium carbonate which when tightly packed, i. e. mechanically packed or tamped, in an ordinary large sugar barrel weighs but 200 lbs. per barrel, is submerged in a boiling solution of a water-proofing sub to stance, for example: stearic acid in the prothoroughly penetrated throughout the solid Lpplieation filed l Fehruary 9, 1925. Serial No. 8,037.

portions of approximately to 1% of stearic acid to 99 to 99% of the aforesaid mixture.. The mixture is allowed to stand until the water-proofing substance is mass treated and any water in the massis evaporated eitherin vacuo or under atmospheric pressure. I l

After the removal of any water, the'residual mixture is subjected toa prolonged heating operation, for example: for a period of minutes at a temperature sufficient to effectively water-proof the same as evidenced by test portions taken from time to time. When a test portion shows that the mass so tested will virtually float indefinitely on water, whereas the untreated mass will rapsink therein, the heating is discontinbe packaged and shipped.

, The mixture so obtained is then reduced to a finely pulverized condition in a suitable mill or otherwise, preferably to such extent that the particles of the same approximate 200 mesh in size. a

. While I prefer to employ stearic acid, because of the fact that it is a digestible fat and therefore subject to decomposition when absorbed into the digestive tract of the larvae, nevertheless, other waterproofing substances, such as tallow, lard oil, cocoa butter and the like ma also be employed. Also the proportions 0 the water-proofing substances so employed may, of course, vary from the proportions herein given of to' 1%, ut the aforesaid proportions are found to impart excellent results.

Preferably the temperature to which the mixtureisheated in the heat treatment 'referred to, ranges between 220 C. to 240 C., but the same should be sufiicient to render the material water-proof and water repellent and also to cause the water-proofing material to thoroughly penetrate into the calcium carbonate treated.

While I prefer a light, flutfy,calcium car bonate of the type which when so waterproofed will fioaton water, other light flufiy fillers, such as for example, magnesium car- 0 bonate, or other compounds capable of cites an impregnated insecticide, I have found that tureis highly efiective and suitable, espefor many purposes the herein described mixcially as the insecticidal properties of the Paris green are absolutely unimpaired because of the same not having been impregna'ted with a digestive fatty acid or the like, and therefore, even incipient digestion is not necessary before the poisonous properties of the Paris green become efi'ective."

While I preferably-employ 4% of an insecticide such as Paris green, obviously the percentages may vary below or above this' amount to suit the particular requirements in the locality where the product is employedand other insecticides, such as for example, calcium arsenate .or other like insecticides which are suitable for the requiremen'ts of the user, may be employed without departing from the spirit of. my invention as covered in the appended claims.

VVhilepreferably no solvent is required in the production of the insecticide or the larvicide product herein described, with the reason that under heat and constant stirring the small percentage of stearic acid employed will distribute itself-throughout either in fine, light porous, flufl'y carbonate as it comes from the drier, or throughout the wet mass of carbonate as it comes from the ordinary filter press which usually carries from to 7 0% .of water. If the wet process is employed, it is preferably to first disintegrate the stearic ally emplo ed when operating in accordance with the a ove described wet method.

. Having thus described my invention, what I claim and desire to obtain by Letters Patent of the United States is:

1. A larvicide containing less than 5% a rendered water repellent and capable of floating for long periods of time on water prior to the incorporation of the Paris green therewith. r

2. A larvicide comprising 4 parts of Paris green and 96 parts of calcium carbonate and a small proportion of a water-proofing substance in the proportions of about one part of such water-proofing substance to 99 parts of the other two ingredients, and the particles of said calcium carbonate having been separately water-proofed and rendered water repellent and capable of floating for long periods of time on water prior to the incorporation of the Paris green therewith.

3. A larvicide containing less than 5% of Paris green, less than 2% of digestible fatty animal acid and in excess of 90% of light fiuify, inert filler the same being homogeneously incorporated together and the particles of said inert filler having been separately water-proofed and rendered water repellent and capable of floating for long periods of time on water prior to the incorporation of the Paris green therewith.

Signed at Ambler, in the county of Mont- 'gomery and State of Pennsylvania, this 5th day of February, 1925.

BENJAMIN F. WALLACE.

. acid into fineparticles and stir'the same into f the cool wet slurry or soup of carbonate and water as it comes from the filter press. Under the influence of the heat'and the steam generated, the stearic acid becomes uniformly 'and homogeneously distributed through the entire mass. The water-proofing action does not commence until after all the steam is evaporated and the heat has been raised to a temperature considerably above the boiling point of the Water, for example, from 200 C.

and upwards.

When performing the dry process, the stearic acid is first finely shaved and then mixed into the dry flufl'y mass of carbonate whereupon a reaction occurs very rapidly and at a considerably lower heat, say for example, around 140 C. to 160 0., than is usu- 

